An optically active medicine or its intermediate is generally required to be highly chemical purity and highly optically purity. Therefore, it is a very important problem to establish the process for preparing an optically active secondary alcohol with highly chemical purity and highly optically purity.
As one of the methods for preparing an optically active secondary alcohol, it is known that an optically active secondary alcohol is prepared by hydrogenating an optically active 1,2-epoxide in the presence of palladium catalyst. According to this method, there is obtained not only an object secondary alcohol, but also its position isomer, a primary alcohol. In order to prevent the production of a primary alcohol, various studies have been done.
For example, the following methods (a) to (d) are reported.    (a) The reaction is carried out in the presence of sodium hydroxide in catalytic amount (Lisa M. SCHULTZE et al., Tetrahedron Lett., Vol. 39, p1853–1856 (1998)).    (b) The reaction is carried out in the coexistence of ammonium formate (Peter S. DRAGOVICH et al., J. Org. Chem., Vol.60, p4922–4924 (1995)).    (c) The reaction is carried out in the presence of palladium-ethylenediamine complex as catalyst (Hironao SAJIKI et al., Chem. Commun., p1041–1042 (1999)).    (d) The reaction is carried out in the coexistence of borane-tert-butylamine complex (Michel COUTURIER et al., Tetrahedron Lett., Vol.42, p2763–2766 (2001)).
In case of above method (a), it is possible to prevent the production of a primary alcohol, but the corresponding ketone is prepared in the course of the reaction. As many of the ketones are resemble to the object secondary alcohol in boiling point, and they are hardly separated and isolated by the usual separation method such as distillation, etc.
In case of above method (b), an excess amount of ammonium formate is required. In case of above methods (c) and (d), the respective amine complex must be previously prepared.
Therefore, there has been much room for improvement of the above known methods for preparing a secondary alcohol from the view point of the industrial production.
The present inventors have been earnestly studied to solve the above problems and as a result, have been found that when preparing a secondary alcohol by hydrogenating a 1,2-epoxy derivative in the presence of palladium catalyst, only by adding thereto a small amount of an amine, productions of not only a primary alcohol, but also the corresponding alkane and ketone as by-products, are prevented and that the object secondary alcohol is prepared in a mild condition with highly chemical purity and highly optical purity. Thus the present invention has been completed.